Process of producing fertilizer.



1,158,711. NoDrawing. Original application filed December 17, 1910,Serial No. 598,127. Divided and this application ED em res rarnnr era-eaSPENCER B. NEWBERRY AND HARVEY N. BARRETT, BAYBRIDGE, OHIO.

.Speei fication of Letters Patent.

'rnocnss or rnonocme FERTILIZER.

Patented as. a, 1915.

- filed March 15, 1912. SeI'ialNO. 684,014.

I To all whom it mag concern:

Be it known that we, SPENCER B. NEW- BERRY and HARVEY N. BARRETT,citizens of the United States, residing at Baybridge, i'n the'countypfErie and State of Ohio, have invented a certain new and usefulImprovement in Processes of Producing Ferti1izer,*o f which the,following is a specifiphates to high temperature, with-the addi-.

tion of certain reagents in very small proportion, under certainspecialconditions as hereinafter described. We have discovered that naturalphosphate may be rendered citrate soluble or suitable for fertilizingpurposes by calcina-tion, and that such process of calcination iscommonly shortened by the association therewithof certain reagents. -Wehave experimented with many" conditions and substances all of which,

it is of course unnecessary-to here set forth in detail, bu'twe shalldescribe some of the conditions of our operation and some of oursubordinate discoveries as a basis for the broad claims which we desireto make. By natural phosphates we mean phosphate rock consistingessentially of phosphate of calcium or phosphate of aluminum and phos-''phate of iron,fal"so apatite, phosphorite,

guano, bone phosphate or other forms of mineral or animal phosphatewhich contain phosphoric acid-ina form substantiallyinsolublein ammoniumcitrate solution andv unavailableyin sin-untreated condition, for

' uralphosphates by heating themwith rela-- use as a' fertilizer.- I wWe are awarethat during the past fifty years a great number of proposalshave beenmade for making fertilizer from nattively large amounts ofvarious substances. Among the substances proposedmay be mentionedcarbon, lime, alkalis, silicates of alkalis and ofalkaline earths, etc.Many of these processes were intended to be applied only to materialssimilar to Redonda) phosphate, conslstlng of phosphate of aluminum andiron, and are entirely ineffective whenapplied to ordinary phosphaterock, consist- 1ng chlefly of phosphate of calcium. None of theseproposals specified the manner of heating or describes the kind of kilnor furnace to be employed. It is certain that none of the processeshitherto described has ever come into practical use, and that a productconsisting of phosphate of calcium rendered by calcination evenapproximately citrate-soluble, has not, as yet, appeared in the market.I

Our experiments and study of the problem have led to the followingdiscoveries 1. Natural phosphates may, be rendered substantiallycompletely citrate soluble'by calclnatlon alone, under certainconditions oftemperature, atmosphere, and exposure to heat,.without theaddition of reagents.

2. Reagents, if added, act only in an auxiliary manner, the principaleffect of the operation being due to the action of heat and of thegaseous atmosphere of the kiln.

3. Certain reagents, addedto the natural phosphate in very smallproportion, for example to the amount of five to fifteen per centof theWeight of phosphate, have the effect of shortening the time and loweringthe temperature necessary to render the phosphate citrate-soluble.Substances which We have found eflicient for this purpose are alkalis infree or caustic form or in any combinations as alkaline salts orcompounds, preferably in the form of, alkali- .metal hydroxid, carbonateof sulfate.

These substances, when highly heated in an oxidizing atmosphere incontact with natural phosphates, are volatilized and expelled in gaseousform. The act, therefore,

as it would appear, only in a mechanical manner or by their presence, inaiding the transformation of the phosphate into soluthe hosphate, beforeand after the calcin'ation, is substantially the same. The chief -bleform, since the chemical composition of agents in changing thephosphate'to a soluble, state are the 'high temperature and exposuretohighly heated products of combustion, and the various substances abovementioned .are to be regarded as merely auxiliary and unessential exceptfor the subordinate results thereby obtained, such as the shortening ofthe time required for the operation.

The conditions which are essential or at least highly importanttothepractically complete transformation of natural phosphate tocitrate-soluble form are High temperature; sufficiently prolongedheating; a moderately oxidizing or at least non-reductingatmosphere;continual exposure of fresh surfaces of the material to contact with thehighly heated products of combustion.

Conditions which are or may be auxiliary and helpful in bringing aboutthe transterial, as obtained by the use of the revolving kiln, to theconversion of phosphates -into soluble form is, we believe, a new conception, and being essential to success and production of a result notheretofore attained, is claimed as our invention.

As a practical example of our process, .we take ordinary phosphate rockor other natural phosphate and pulverize it withthe addition of fromfive to fifteenper cent. of its weight of one of the reagents abovenamed,

or of a mixture of two or more such reagents.

The pulverizing may be effected by wet or dry process. The groundmaterial isthen introduced gradually into the'upper or feed .end of arevolving cylindrical kiln, lined with refractory material,preferably'of a basic. character, and internally heated by a flame orflames of coal-dust, oil or gas. The

. kiln is slightly inclined toward the fire end,

and revolves at a rate of one revolution in one to two minutes. The fuelis fed into the kiln in intimate mixture with air, and additional air isadmitted in such-amount that g the fuel shall be completely consumed inthe lower part of the kiln, and that a moderately oxidizing atmosphereshall prevail through out the lnterior space, care being taken to avoidadmitting any considerable-excess of I air above that required forperfect*combus-- tion. The temperature in the hottest zone, at aboutone-fourth the length of the kiln from the fire end, is maintained at2500 degrees to 3000 degrees F., accordingto the more or less refractorycharacter of the material treated. The temperature should be regulatedso as tofbring the material to aifsintered or similar-result.

semi-fused and porous condition, and to yield a product of maximum andpractically complete citrate-solubility. This result may generally beobtained at a temperature between the limits above stated.

' The operation of the kiln is such that the raw material, entering atthe upperend, travels slowly and continuously toward the source of heat,and by the rotary motion to -which it is subjected, is agitated andturned over in such manner as constantly to expose fresh surfaces to theaction of the highly heated products of combustion. Before reaching thehottest zone, easily volatilev products, such as water and carbondioxid, are expelled, and at the highest temperature of the kiln, sulfurdioxid' and alkalis, if

4 present, are Wholly or in larger part volatilized.

The calcined product issues from the kiln in the form of soft, porousclinker. This is ground to powder and is then ready for use asfertilizer or as an ingredient of commercial fertilizers.

The time of heating required varies with the character of the rawmaterlalypresence and proportion of reagents, and temperature employed.Wehave found, however, that raw 'material containing about-ten per cent.

of-reagent such as soda'or sodium sulfate is brought to practicallycomplete solubility by exposure of thirty minutes to one hour to a"temperature of 2500 degrees to 3000 degrees F.

We have found it advantageous, for the sake of economy, to make useof-well-known appliances, in connection with the revolving kiln, for thecollection of volatilized alkalis and sulfur dioxid, and for heatirfgthe entering air by contact withthe hot clinker discharged from thekiln.

We wish it to be understood that the conditions highly important if notnecessary for .efl'ective. conversion of; natural phos phate' ofcitrate-soluble. form, by our process are prolonged exposure to highlyheated gases, with such mechanical agitation as will constantly presentfresh surfaces of mat rial to contact with 'the highly heated gaseousatmosphere. These conditions are most perfectly produced in a revolvingkiln;

but wedo not intend to restrict our claims to the use of' that apparatussince any type of or furnace which the .conditions' 1 above named aredeveloped would'produoe a We'claimr 1 The process of renderinginsolublevcalcium phosphate .citratesoluble iwithout changingitschemical characteristics, which consists in calcining powdered-insoluble Cat 7 be rendered citrate-soluble and the alkali.v

cium phosphate in the "presence'of such an amount of an alkali-metal"saltand at such 1 temperature that the calcium phosphate will metal saltwill be decomposed and substantiallyexpelled without permanent reactionwith the calcium phosphate.

2. The process of'making fertilizer by calcining natural phosphate witha small percentage of an accelerating material volatile at thetemperature ofcalcination and consisting of an'alkali-metal salt.

3. The process ofmaking fertilizer by calcining natural phosphate withfrom 5 to 15' per cent. of an accelerating material volatile at 'thetemperature of calcination and consisting of an-alkali-metal salt.

4. The process of making fertilizer by calcining natural phosphate witha small percentage of accelerating material volatile at the temperatureof calcination and consisting of alkali-metal salt at a temperature offrom 2500 to 3000'degrees Fahrenheit.

5. The process of making fertilizer by calcining natural phosphate withfrom 5 to.15 per cent. of an'accelerating material volatile at thetemperature of calcination and con sisting of an alkali-metal salt at atemperature of from 2500 to 3000 degrees Fahrenheit.

6. The process of-making fertilizer by calcining natural phosphate withfrom 5 to 15 per cent. of an accelerator consisting of an alkali-metalsalt at a temperature of from 2500 to 3000 degrees Fahrenheit, andagitating the materials and mixing them together at this temperatureuntil the volatile constituents of the accelerating material aresubstantially expelled and the residue is rendered substantiallycitrate-soluble.

7. The process of making fertilizer by calcining natural phosphate witha small percentage of substance. principally. volatile at thetemperature of calcination. 8. The process of making fertilizer bycalcining natural phosphate with alkali-metal compound principallyvolatile at the temperature of calcination.,

9. Theprocess of making fertilizer by calcining natural phosphateqwith 5to 15 per cent. of alkali-metal compound principally volatile at thetemperature of calcination.

10. The process of making fertilizer by calcining natural phosphate withalkalimetal compound principally Volatile at-high temperature until thealkali-metal compound is substantially expelled and'the phosphaterendered citrate-soluble.

11. The process of making fertilizer by calcining natural phosphate with5 to 15 per cent. of alkali-metal compound principally volatile at hightemperature, at 2500 degrees to 3000 degrees F., until the alkalimetalcompound is substantially expelled and the residue renderedsubstantially cit- I 13. The process of making fertilizer by pulverizingnatural phosphate, mixing therewith 5 to 15 per cent. of alkali-metalcompound principally volatile at high temperature, and calcining themixture at 2500 degrees to 3000 degrees F., until the alkalimetalcompound is substantially expelled and the residue renderedsubstantially citrate soluble and brought to approximately the samecomposition as the phosphate treated except for loss of volatile matter.

14. The process of rendering insoluble calcium phosphate citrate solublewithout material change in its chemical composition, which consists incalcining powdered insoluble. calcium phosphate in the presence of suchan amount of alkali-metal compound and at such temperature that thecalcium phosphate will be rendered citrate soluble and the alkali-metalcompound. will-be decomposed and substantially expelled.

15. The process of making fertilizer by pulveri'zing natural phosphate,mixing therewith 5 to 15 percent. of alkali-metal compoundprincipally'volatile at high temperature, calcining the mixture atemperature of 2500 degrees to 3000 degrees F in such manner that thematerialshall travel continuously toward the source of heat and shall beso agitated as to present fresh surfaces to contact. with highly-heatedproducts of combustion, until the alkali-metal compound is substantiallyexpelled and the residue rendered substantially citrate-soluble, andpulverizing the calcined product.

Signed at Baybridge Ohio this twelfth day of March 1912.

SPENCER B. NEWBERRY. V "HARVEY N. BARRETT. Witnesses:

HATTIE M. MEGGITT, IRVIN H. NUBER.

